This invention relates generally to touch sensor panels of the type that respond to contact by a user to provide an input to a control circuit and more particularly to a touch panel having graphics to indicate the functions associated with a particular portion of the touch sensor panel.
The use of capacitive touch sensor panels as an input device for various applications is well known. In order to associate a particular function being invoked by the actuation of one particular touch pad, a graphic symbol is located on the touch panel juxtaposed with the associated switch. While efforts are made to make the graphics pleasing in appearance, their presence tends to be obtrusive when used in design concepts attempting to achieve clean, non-functional lines. In such application, it may be desirable to provide a control panel that completely blends into the background in order to disguise the presence of the control panel until its use is required.
One approach to impart a pleasing appearance to a touch panel is suggested in U.S. Pat. No. 4,855,550 issued to Schultz, Jr. In the Schultz, Jr. patent, outer electrodes of finely ground glass black glass particles and a conductive metal powder are covered with a non-conductive white ceramic enamel to hide the dark color of the electrode except for a small exposed area which may define a graphic symbol. The exposed area provides a touch pad for contact by a human body member. Although the touch panel disclosed in Schultz, Jr. may have an overall light-colored appearance, the graphic symbols remain visible at all times, and hence obtrusive. Furthermore, the efforts to reduce the obtusiveness of the graphics has a tendency to interfere with their functionality.